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            width: 300px;
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            /* border-width: 5px;
            border-style: solid;
            border-color: #901d1d; */
            /* 边框的复合写法 简写： */
            /* border: 5px solid #901d1d; */
            /* 上边框 */
            border-top: 5px solid #901d1d;
            /* 下边框 */
            border-bottom: 5px dotted aqua;
            /* 左边框 */
            /* border-left */
            /* 右边框 */
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